SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4a4a98f3d3a75dbe70eb09fbdbfc1f899106dadb4e9ef5876900bcaecff918' 
  AND token = 'm8WpLYGj2uFxwTFPBinag0ofmVzB8L+QtpVWVzqLH+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}